RF SWITCH SPST ?

[bowen44]

The question I had on the rf switch.
In a drawing it reads " RF INPUT LEVELS ARE FOR LESS THAN 1 dB COMPRESSION
("ON" CONDITION) and LESS THAN 3 dB DEGRADATION IN ISOLATION ("OFF"
CONDITION) AT LEVELS 3 dB BELOW THOSE SHOWN." I am not familiar with the
term "compression" and "degradation" as they use it here. The drawing shows
Flag Note 5 in the column heading of RF IN. which gives:
1.0 - 10.0 MHZ................ +7 dBm
10.0 - 50.0 MHZ.............. +7 dBm
50.0 - 200 MHZ............... +13 dBm
so apparently it has to do with input power.

Any help you can give me on this would be appreciated.

 

[JBE]

Have you read "Modern Definition of Terms" in

http://www.minicircuits.com/appnote/sw13-2.pdf

? I guess that you will understand better "your switch"

 

[alva]

From the way that you worded your post I am assuming that you are reading a mini circuits catalog. Half of practical RF engineering is being able to decode the way manufacturers write the specs for their parts. 1 dB compression is a common term. I think JBE's suggestion is a good one. Although Minicircuits does not really make anything (they purchase is bulk and sell in low quantities) they have some good basic tutorials.

That being said, I will try and help though. 1db compression is most commonly used in the description of amplifiers. In the linear nominal state of an amp, a increase in the input power causes a increase in the output power. The ratio of output power to input power is the gain. Put a -10 dBm signal in an amp with 5 db gain and you get -10dBm + 5dB = -5 dBm out. Pretty simple. Well that is good for the linear region but everything has its limits. There will be a point at which for a given input power you will not get the same gain. For example, if you put a -5 dB signal into the same 5 dB gain amp as stated above you might only get 4db of gain for an output power of -5 dBm + 4dB = -1dBm. The gain has dropped off 1dB. So instead of getting 0dB out you only get -1db. This is referred to as the 1dB compression point because your gain has been "compressed" 1 db from the nominal linear gain.

What the hell does this have to do with a switch you might ask? The 1 dB compression point is a way of specifying the maximum input power that of a device. Rather than saying our 5dB gain amp has a maximum input level of -6 dBm they say the 1 dB compression point is -1dBm (usually referred to the output) For your switch app what Mini Circuits is trying to say is...if you keep your input power below the levels listed..+7dBm for 1 to 10 MHz etc... you will not experience any insertion loss due to gain suppression.

 

[bowen44]

Thanks for all the info JBE and alva. It helped me to get a better understanding of an RF Switch.